Note: Descriptions are shown in the official language in which they were submitted.
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~r~~ rryh~pAN~C HEARING INSTRUMLN'1
FIELD OF THE INVENTION
The invention herein generally relates to a miniature electroacoustic
instrument
and, in particular, a peritympanic hearing instrument suitable for use in
humans.
BA KGROUND OF THE INVENTION
Hearing instruments typically are custom-designed to suit the anatomical and
audiological needs of as individual user. Because custom-made devices can be
very
costly, it is desirable to mass-produce a hearing instrument that is
relatively
inexpensive, readily adaptable to most users' anatomical and audiological
1o requirements, and inconspicuous and lightweight.
There are significant challenges associated with the development of mass-
produced hearing instruments. Although the structure of the external auditory
canal
generally is a sinuous, oval cylinder with three sections, it varies
significantly
depending on the particular individual. Traversing the canal towards the
tympanic
i 5 membrane, the first section is directed inward, forward, and slightly
upward. The next
section tends to pass inward and backward. The final section is carried
inward,
forward, and slightly downward. The outer portion of the ear canal is
surrounded by
cartilaginous tissue, with the inner portion being surrounded by bone. The
canal is
lined by a very thin lining of skin, which is extremely sensitive to the
presence of
2o foreign objects. Further details of the path and contours of the external
auditory canal
are described in U.S. Patent No. 4,870,688, issued to Barry Voroba et al., and
in U.S.
Patent No. 5,701,348, issued to Adnan Shennib, both of which are incorporated
herein
by reference.
U.S. Patent No. 4,870,688 describes an in-the-canal miniaturized hearing aid
25 contained within a prefabricated earshell assembly composed of a hollow
rigid body
with a soft, resilient covering fixed to its exterior. The microphone,
receiver,
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2
amplifier, and battery are ail wholly contained within a prefabricated modular
sound
assembly which snaps into a patient-selectable prefabricated earshell
assembly. The
soft, resilient covering that is affixed to the exterior of the rigid core is
intended to
allow the cylindrical or elliptical shape of the in-the-canal hearing aid to
more easily
conform to the individual variations in a user's auditory canal:
U.S. Patent No. 5,701,348 describes a hearing device having highly
articulated,
non-contiguous parts including a receiver module for delivering acoustic
signals, a
main module containing all of the hearing aid components except the receiver,
and a
connector that is articulated with both the receiver module and the main
module to
to permit independent movement of the receiver and main modules. Separation of
the
receiver from the main module, and the receiver's articulation with respect to
the main
module, is intended to provide at least two degrees of freedom in movement and
independent movement of the receiver module with respect to the main module,
and
vice versa.
~5 Attempts have also been made to provide inserts intended to be used as a
part of
a hearing aid device. U.S. Patent No. 2,487,038, issued to Jasper Baum,
describes an
ear insert shaped for insertion into the conchs or the outer cavity of an ear.
It includes
a series of ball-shaped ball-like wall sections each made with sufficiently
thick walls so
as to give them great stiffness and prevent substantial distortion of the
cross-section of
2o the sound-passage portions extending therethrough under the action of
external bending
forces when the insert is inserted into the curved space of the outer ear
cavity. The
ball-like wall sections are interconnected by short neck-like sections to
readily flex and
take up substantially the entire deformation to which the channel insert is
subjected.
Thin flexible, skirt-like protrusions project in outward and rearward
directions from
25 the ball-like wall sections to become wedged against the surrounding
surface portions
of the outer ear cavity for automatically establishing therewith an acoustic
seal.
U.S. Patent No. 3,080,011, issued to John D. Henderson, describes an ear
canal insert with a very soft tip with mushroom-shaped flanges. A flexible
mounting
tube is considerably stiffer than the material of which the mushroom-shaped
head
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poziion flanges are farmed so that it earl be used to force the insert
port~.on of the device
into the ear canal.
U.S. Patent No. 5,2x1,407, issued to Gary L. Ward et al., describes earmalds
that cozivey amplified sound &orn the hearing aid to the ear. An acoustyc
cc~nducdon '
tube extends into the ear canal and a flanged tip an the canductian tube
creates a
resonant cavity between the tip and the tytnparlic membrane. The tip is
constructed of a
flexible material to form a sealed cavity adjacent the tympanic membrane,
permit the
seal to be obtained with aaly slight pressure against the wall of the ear
canal, and permit
the tip to be oscillated by the natural, unamplified sounds which arrive by
air
conduction through the ear canal, so that the oscillation can raise the
resonant
frequencies ofthe cavity.
International Pubi:cation WO 92113430, published under the Patent Cooperation
Treaty (PCT) as August 6, 1992, diacioscs a hearing aid configured and
dimensioned so
as to be inserted past the cartilaginous part of the external auditory canal
and into the
bony part of the external auditory canal.
U.S. Patent No. 3,527,901, issued to Robert L. Geib, describes a hearing aid
adapted to be wom entirely within the car of the user, where substantially all
or at least
a major portion, of the housing is made of a relatively soft resilient
material.
U.S. Fatent No. 5,220,612, issued to George C. Tibbctts er al. discloses an in-
the-ear electroacoustic transducer constructed to limit the effect of
acGretic~n of cerucuea
on acoustically active surfaces to preveltt cerunnen from plugging passages
for acoustic
and energy to the tympanic trlembrane and to facilitate the removal of cerumen
from the
transducer by the user.
Despite numerous attempts including those described above, tr~rre remains a
need for a mass-produced hearing instrument that is relatively inexpensive,
re$dily
adaptable to an individual's atomical and aetdiolo°ical reguirernents,
and that ZS
inconspicuous alai lightweight. It has been discovered that the development of
a
prosthetic device that occupies the re~i.on traditionally filled by an in-the-
canal (ITC)
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device, as well as extending significantly iota the peritympanic region, is
ir~robable at
best without a device that will allow deep penetration into the ear canal by
the heating
instruatrnt. Curtent "one-size-fits-all" hearing instruments are either of the
ia-the-ear
(lTlr) - -or ITC variety. Soxue have the ability to arcoZnznodate the first
bend in the car
canal. However, convczztional hearing instrtuttents fail to adequately and
simultaneously accommodate thr first and second bends of a typical ear canal
and are
generally not capable of comfortably extending significantly into the
peritympanic
region.
Ii has also been recognized that hearing instruments typically have stnxll-
diaructer openings, or sound ports, to let sound propagate fpm the receiver to
the
tympanic me~thrane. A common ptnDlem with such devices is that the certuxten,
or
wax, withal the car canal becomes embedded in the device's sound pore.
Physical
properties of cerutrtca make cleaning of the sound port difficult and, indeed,
the
A~LE6~DED SHEET
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4
cleaning process may force the cerumen deeper into the sound port.
Cost is also a major consideration in the development of mass-produced hearing
instruments. It has been discovered that, of all the components in a hearing
instrument, the microphone and receiver (loudspeaker) are generally the most
costly.
Of these components, the receiver is generally the more costly item.
Accordingly,
reduction of the cost of the receiver component can significantly lower the
cost of
manufacturing the hearing instrument. Many receivers are considered to be self
contained in that they are mounted within their own metal housing. Generally,
such
receivers have small solder pads to which electrical connections are made.
Such solder
t o connections are sometimes fragile and have been known to break. During
manufacturing of hearing instruments with such receivers, great care must be
observed
so as not to damage the receiver or the solder connections.
It has further been recognized that the housings for shells used in
conventional
hearing instruments can become difficult and costly to manufacture. Their
shapes are
t 5 generally dictated primarily by the contours of the ear cavity in which
they are
intended to be positioned, but attempts to reduce the cost and difficulty of
manufacturing conventional shells could reduce the available range of shapes
and
contours. Alternatively, the cost of manufacturing and the complexity of the
manufacturing process remain substantial.
2o Accordingly, it is an object of the invention to provide a peritympanic
hearing
instrument that overcomes one or more of the disadvantages associated with
conventional hearing instruments.
SUMMARY OF THE INVENTION
The invention, in its broad form, resides in a hearing instrument as recited
in
25 claims 1 and 7, and a tip for use with a hearing instrument, as recited in
claim 18.
The described embodiments of the invention provide a hearing instrument that
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is positionable in the external auditory canal of a human at a location that
is proximal
to the tympanic membrane. The preferred instrument includes a substantially
rigid
shell that is shaped to enclose a microphone as well as a receiver and that
has a distal
end portion that faces toward the tympanic membrane. The instrument also
preferably
includes a relatively flexible tip member that is connected adjacent to the
distal end
portion of the shell. The tip member includes a hollow body that defines a
passage
extending between its ends for the communication of acoustic signals through
the tip
member between the shell and the tympanic membrane. The hollow body of the tip
member is sufficiently deformable to conform to the auditory canal. It is also
to sufficiently rigid to resist collapse of the passage upon insertion in the
canal. An axis
of the passage through the tip member is moveable at an angle with respect to
the axis
of the shell so that the hearing instrument can navigate the path of the
external auditory
canal upon insertion of the instrument toward the tympanic membrane and beyond
the
second bend of the canal. The tip member is positionable to seal against an
inner
1 s surface of the canal .
An exemplary embodiment of the hearing instruments also includes a joint
positioned to provide a connection between the distal end portion of the shell
and the
tip member for rotation of the tip member passage's axis with respect to the
shell's
axis. This rotation is accomplished about a rotational axis that is
structurally
2o predefined by the joint.
It is also preferred for the shell to be shaped in such a way as to enclose
the
receiver's motor and diaphragm components. Such a shell eliminates any need
for a
separate receiver housing for enclosing the motor and diaphragm components,
thereby
reducing the cost of the receiver as well as the overall cost of the
manufactured hearing
25 instrument.
It is further preferred for the tip member of the hearing instrument to
include
the hollow body as well as protrusions such as flanges that are positioned
adjacent to
the body portion so as to extend radially outwardly. In such a preferred
configuration,
a perimeter portion of each of the protrusions is positionable against the
inner surface
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6
of the external auditory canal to help center the tip member in the canal.
In a modification, the shell of the hearing instrument includes multiple shell
portions, each having an engagement surface that extends toward the shell's
distal end.
The shell portions are assembled along their respective engagement surfaces in
order to
enclose the microphone and receiver components of the instrument.
It is also preferred for the tip member to include a wax guard surface that is
positioned adjacent to the distal end portion of the tip member's hollow body.
The
surface should traverse the diameter of the tip member's elongated passage in
order to
prevent undue ingress of cerumen from the external auditory canal into the
elongated
to passage.
In order to prevent any substantial collapse of the elongated passage through
the
tip member upon insertion of the hearing instrument and bending of the tip
member,
the tip member preferably includes means positioned along a length of the
hollow body
and extending adjacent to the elongated passage for resisting such collapse.
Such a
t5 structure permits elimination of the need for a bendable joint between the
tip member
and the remainder of the hearing instrument. An example of such means includes
a
spring that extends adjacent to the passage.
BRIEF DESCRIPTION O~ THE DRAWINGS
A more detailed understanding of the invention may be had from the following
2o description of preferred embodiments, given by way of example, and to be
read and
understood in conjunction with the accompanying drawing wherein:
FIG. 1 is an exploded view of an embodiment of a hearing instrument having a
two degree-of freedom joint according to a preferred embodiment of the
invention.
25 FIG. 2 is an exploded view of an embodiment of a removable fin section and
joint portion for the hearing instrument shown in FIG. 1.
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7
FIG. 3 is an exploded view of an embodiment of a hearing instrument having a
three degree-of freedom joint.
FIG. 4 is an exploded view of an embodiment of a hearing instrument having a
one degree-of freedom joint.
FIG. 5 is a graphical finite element analysis representation of an embodiment
of
a ball and socket joint before partial assembly.
FIG. 6 is a graphical finite element analysis representation of an embodiment
of
a ball and socket joint after partial assembly.
FIG. 7 is a graphical plot of the forces associated with an embodiment of a
ball
to and socket joint during partial assembly.
FIG. 8 is a cross-sectional side view of an embodiment of an ear tip without a
cerumen guard.
FIG. 9 is a cross-sectional side view of an embodiment of an ear tip with a
cerumen guard.
t5 FIG. IO is a cross-sectional side view of an embodiment of an ear tip with
another embodiment of a cerumen guard.
FIG. 11 is an exploded view of a hearing instrument including an embodiment
of a tip assembly according to a preferred embodiment of this invention.
FIG. 12 is an exploded view of the tip assembly shown in FIG. 11.
zo FIG. 13 is a side view of another embodiment of a tip assembly.
FIG. 14 is a proximal end view of the tip assembly shown in FIG. 13.
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FIG. 15 is a distal end view of the tip assembly shown in FIG. 13.
FIG. 16 is an exploded, cross-sectional side view of a portion of an
embodiment
of a hearing instrument shell used in this invention.
FIG. 17 is an exploded, cross-sectional end view of the hearing instrument
shell
shown in FIG. 16.
FIG. 18 is an exploded, cross-sectional side view of a portion of another
embodiment of a hearing instrument shell used in this invention.
FIG. 19 is an exploded, cross-sectional side view of a portion of yet another
embodiment of a hearing instrument shell used in this invention.
1o FIG. 20 is an exploded, cross-sectional side view of a portion of still
another
embodiment of a hearing instrument shell used in this invention.
FIG. 21 is an exploded, cross-sectional side view of a portion of another
embodiment of a hearing instrument shell used in this invention.
I~FC~RIPTION OF PREFERRED EMBODIMENTS
t 5 The invention will now be described with reference to several embodiments
selected for illustration. It will be appreciated that the invention is not
limited to the
specific embodiments shown in the drawings or described herein. Also, it will
be
appreciated that the drawings are not intended to be to scale or proportion.
The
following description is not intended to limit the scope or spirit of the
invention, which
2o is defined separately in the appended claims.
According to one of its aspects, the present invention surmounts the
aforementioned limitations of conventional. hearing instruments by providing a
hearing
instrument preferably having the equivalent of at least a single rotational
degree of
freedom near its tip. This instrument also can include a cerumen guard.
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9
FIG. 1 illustrates an embodiment of the invention, namely a hearing instrument
having a two degree-of freedom (2-DOF) joint that allows the tip to extend
into the
peritympanic region of the ear canal. One advantage of this arrangement is
that the 2-
DOF mechanism facilitates the navigation of the typical centerline path of an
ear canal.
s After insertion, the stationary location of the 2-DOF joint is preferred to
be in the
vicinity of the second (or distal) bend, i.e., between the second and third
sections of
the external auditory canal, as described above.
By placing the joint and tip so deeply into the ear, it also is possible to
place the
receiver closer to the eardrum to permit lower gain amplification to be used.
The
1o reduction in the level of amplification required by the instrument reduces
the amount of
power needed to drive the instrument amplifiers, which directly translates
into a
smaller battery and a smaller prosthesis.
Another advantage is that the 2-DOF jointed tip allows the generation of a
seal
near the bony region of the ear canal. An appropriate seal in this region can
~5 substantially mitigate the occlusion effect - whereby low frequency signals
and noise
are overly pronounced. The 2-DOF joint tip may be designed as a two-piece
assembly
such that a finned section of the tip member can be separated from the joint
portion. A
simple but effective retaining device such as a screw or snap can be used to
effect
assembly and permit disassembly. If a tip becomes una<;ceptably contaminated
with
2o wax, one could simply remove the old tip and subsequently screw or snap in
a new
one, rather than cleaning it.
Referring to FIG. 1, an instrument shell 1 is composed of an upper portion lA
and a lower portion 1B. It is shown in an exploded view for clarity. When
assembled,
the shell is designed to fit comfortably within the ear canal. Construction of
instrument
25 shell 1 from multiple shell portions such as upper portion lA and lower
portion 1B has
been discovered to be beneficial from both the standpoint of cost reduction
and ease of
manufacturing. The first bend of the external auditory canal is generally a
severe
bend, as described earlier. Referring specifically to FIG. 1, the shell 1 is
shaped to
conform to this first bend so that it can fit comfortably within the user's
ear canal. It is
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of course, preferred that the primary consideration in determining the exact
shape of
the shell should be the user's comfort when wearing the hearing instrument and
that
cost and manufacturing ease should be secondary considerations.
Conventional hearing instruments generally include cup-shaped shell
5 components, such as those suggested in Voroba U.S. Patent No. 4,870,688, and
in
Shennib U.S. Patent No. 5,701,348. Nevertheless, it has been discovered that
the use
of injection molding processes to form a cup-shaped shell can be inadequate. A
standard injection mold cannot be easily adapted to form the ideal contours of
a
comfortable shell because the resulting shell would be difficult to extract
from the mold
1o due to the first bend contours. Also, it would be difficult to extract the
center core of
the mold; especially if a large multicavity mold is used. Alternatively, a
complicated
and expensive injection mold structure would have to be employed in order to
form the
complex contours of the shell's outer surface.
It has been discovered that, instead of the use of a cup-shaped shell
component,
the use of a so-called "clam" shell configuration such as the one illustrated
in FIG. 1
has many benefits. It can be more easily formed using conventional injection
molding
processes because each of the shell portions or clam-shell halves can be
easily extracted
from the mold tooling. At the same time, such shell components can be easily
provided with alignment bosses and alignment recesses so that the shell
portions can be
2o assembled with ease and with accuracy to form the shell. Accordingly, the
primary
consideration for the selection of the contours of the shell can be the
comfort of the
user while using a simple injection molding and assembly process and while
maintaining a low manufacturing cost.
As shown in FIG. 1, the shell portions lA and 1B are most preferably provided
with engagement surfaces 1C and 1D, respectively, that extend from the
proximal
portion of the shell 1 (the larger diameter portion) to the distal end portion
of the shell.
It is noted that these surfaces can include alignment features such as tongue-
and-groove
joints, etc. The shell portions, lA and 1B are substantially mirror images of
one
another and each of the shell portions lA and 1B represents approximately one
half of
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the shell. It is also apparent in FIG. 1 that each of the shell portions lA
and 1B
include internal contours and surfaces that permit the formation of internal
compartments when the portions are assembled. It is these internal
compartments that
house the various components of the hearing instrument, including the
instrument's
s receiver, microphone, electrical circuit, and other conventional hearing
instrument
components. The clam-type shell and internal compartments allow the optional
use of
total automation using simple pick and place equipment.
Referring still to FIG. 1, a portion of the 2-DOF joint S, which is in the
form of
a ball and socket joint in this particular embodiment, can be formed at one
end of the
1o shell 1, obtaining the 2-DOF as follows: (1) rotation about the predefined
axis of the
detents or pin-bosses 2A and 2B on the ball 2 is allowed; and (2) predefined
rotation in
the plane of the slot 17 at the tip of the shell 1 is also permitted.
More specifically, still referring to FIG. 1, the joint 5 is formed by
engagement
by ball 2 in a cavity defined by the assembly of shell portions lA and 1B to
form shell
15 1. It will be understood that the cavity formed by shell 1 snugly
accommodates ball 2
while permitting rotation. Such engagement most preferably prevents unintended
separation of ball 2 from the socket in shell 1, yet may preferably be adapted
for
intended dis-engagement of ball 2 from shell 1, if desired, so that the tip
member can
be removed and replaced by the user of the hearing instrument.
2o In this embodiment, radially outwardly extending detents 2A and 2B on ball
2
share a common, predefined axis and are preferably diametrically opposed from
one
another on opposite sides of ball 2. These detents 2A and 2B together define a
rotational axis about which ball 2 can rotate with respect to shell 1. Such a
rotational
axis predefines one DOF so that a tip member 4 of the hearing instrument can
be
25 rotated about that predefined axis.
To provide a second DOF for joint 5, a slot 17 is defined by the assembly of
shell portions lA and 1B of shell 1. Slot 17 is sized and positioned to
capture detents
2A and 2B of ball 2 in such a way that detents 2A and 2B can travel within the
slot 17
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in the general plane of slot 17. Accordingly, slot 17 cooperates with detents
2A and
2B to provide a second predefined axis of rotation between ball 2 and shell 1.
The
actual rotational axis provided by the interaction of detents 2A and 2B with
slot 17 is
substantially perpendicular to the plane in which the slot 17 resides.
A connection 6 is provided between ball 2 of ball joint 5 and the body portion
of tip member 4 as will be described later. Tip member 4 has a substantially
hollow
body that defines a passage 18 extending between its ends. Although not shown
in
FIG. 1, passage 18 extends throughout the length of tip member 4 and along its
axis
and even extends outwardly to the rear or proximal end of ball 2 in this
embodiment.
1o In this manner, passage 18 acts a conduit for communication of acoustic
signals
between the body of the hearing instrument and the tympanic membrane. Passage
18 is
preferably elongated, having a length that is larger than its diameter.
Tip member 4 also includes in this embodiment a plurality of circumferential
fins 19 that are connected to the hollow body portion of tip member 4 and
exteml
radially outwardly from the hollow body. Protrusions such as fins 19 are not
required
but, if desired, fins 19 can be formed integrally with the remainder of tip
member 4
such as by a molding operation although separate assembled components are
contemplated as well. Further details of optional fins 19 on tip member 4 will
be
provided later.
2o Various nests, compartments, and other alignments can be seen in the shell
illustrated in FIG. 1. These nests accommodate the hearing instrument's
receiver,
microphone, and electronics, while the alignment bosses and mating sockets on
the
shell portions lA and 1B insure proper alignment of the shell halves. Outer or
proximal face plate 3 and tip member 4 of the hearing instrument act in
concert with
portions lA, 1B to enclose and protect the electroacoustically active
components of the
instrument (not shown).
Tip member 4 in this embodiment is constructed such that it contains an
integral
ball 2 with pin-type bosses 2A and 2B. These bosses mate with the appropriate
slot 17
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13
in the shell halves to form the 2-DOF joint. Highly-compliant and biocompadble
fins
19 are preferred on tip member 4 in order to provide an effective seal in the
ear canal.
Because the tip fm 19, or rings, are preferably thin and constructed of a low
modulus,
low durometer material, the tip member 4 will provide a high level of comfort
for the
user even when it is inserted into the bony region of the ear.
It is preferred for the modulus of elasticity for the tip rings 19 to be less
than
about 3447.5 kPa (500 psi). A modulus of elasticity of less than about 344.75
kPa (50
psi) is most preferred, thus permitting greater comfort to the user yet
affording
sufficient thickness to the rings to facilitate manufacturing of the tips. The
resulting
thickness of the fins 19 is preferably on the order of about 0.5mm (20 mils),
although
other thicknesses and materials are contemplated as well.
It also is preferred that the shell 1 of the instrument be composed of a
substantially biologically inert, generally rigid substance with a low
coefficient of
friction and which is amenable to mass-production techniques, such as, for
example,
~5 NORYL~'~"', manufactured by GE. Other alternative materials are
contemplated as well.
The shell 1 can be partially or completely enshrouded by a layer of compliant,
biocompatible material (not shown) to increase the comfort experienced by the
user and
to help protect the articulated portions of the instrument.
FIG. 2 illustrates a 2-DOF joint designed to allow the finned tip member to be
2o easily replaced by a user, if desired. The tip assembly includes a joint
member 7 and a
finned tip member 8 which may be releasably fastened using a connector such as
screw
9 and threaded socket 10. Other releasable fasteners, such as a snap connector
and
other known fastening systems, also may be used. Such an assembly is
especially
benefcial when the joint member 7 is permanently engaged in the shell's
socket. Joint
zs member 7 is preferably formed from a relatively rigid material as compared
to tip
portion 8. The extension of passage 18 (FIG. 1) through the ball of joint
member 7 is
indicated by " 18A."
FIG. 3 illustrates another embodiment of the present invention, having a three-
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14
degree of freedom ball-and-socket joint. Here, socket portion 16 of the 3-DOF
joint is
formed at one end of a shell having shell portions 11, 12. Similar to the
structure
illustrated in FIG. 1, the device in FIG. 3 can include an outer face plate 13
and a tip
member 14. Tip member 14 is preferred to be constructed such that it contains
an
integral ball 15 as well as compliant, biocompatible fins that provide an
effective seal
in the external auditory canal proximal to the tympanic membrane.
The socket portion 16 of the 3-DOF joint engages the integral ball 15 in such
a
way as to permit free rotation of the ball within the socket about three axes
of rota'on.
Such predetermined rotational axes provides a wide range of adjustments to
conform to
to the specific contours of an individual's external auditory canal. Although
such
unlimited freedom of rotation may be preferred in some circumstances, it has
been
discovered that the joint illustrated in FIG. 1 having two predetermined axes
of rotation
or a joint having only one predetermined axis of rotation (to be described
later with
reference to FIG. 4) are very beneficial. Although the exact configuration of
users'
t5 canals cannot be anticipated precisely, results of surveys of measurements
can predict
the general contours of normal ear canals. Accordingly, predefined axes of
rotation (or
a single predefined axis), if oriented to accommodate normal ear canals, can
bring
about an improved hearing instrument configuration as it is installed is a
normal canal.
Unlimited articulation of the tip component on the other hand can perhaps
inhibit
2o proper installation in some circumstances because there is little control
over the
movement of the tip with respect to the remainder of the instrument.
A hearing instrument incorporating a single-degree of freedom (DOF) revolute
joint is shown in FIG. 4. In the device illustrated in FIG. 4, a portion of
the 1-DOF
joint can be formed at one end of the shell, which in this embodiment includes
shell
25 portions 51 and 52. Various nests and other alignment features can be used
to
accommodate the hearing instrument's receiver, microphone, and electronics,
while the
alignment bosses and mating sockets insure proper alignment of the shell
halves 51 and
52. Upper subshell 51 and lower subshell 52 can, as with previous embodiments,
work in concert with other structure parts, such as face plate 53 and tip
member 54, to
3o envelop and protect the electroacoustical components therein (not shown).
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It is preferred that tip 54 be constructed so that it includes an integral
ball 57
with pin-type detents or bosses 55 (one shown) which mate with the appropriate
recesses, such as recess 56, formed in the shell halves 51 and 52. This
assembly forms
the revolute joint with a single predetermined axis of rotation. It also is
preferred that
compliant fins be provided on tip member 54 to provide an effective seal in
the ear
canal. It should be mentioned that the fins are preferably thin and
constructed of a low
modulus, low durometer material, similar to the embodiments described above.
The ball joint of any of the presented embodiments preferably can be designed
so that it could be engaged and disengaged by the user when desired.
Alternatively,
to the joint components could be dimensioned so that it would be extremely
difficult to
disengage the joint without destroying the socket and/or ball. FIGS. 5, 6, and
7
illustrate exemplary forces that can result from assembly of the joint. The
physical
characteristics of the shell can be modified to suit the desired goal.
FIG. 5 illustrates a baU and socket joint before insertion of the ball into
the
t 5 socket. The ball and socket joint is generally designated by the numeral
"20" . It
includes a socket supported by a tubular portion 24 from which a socket cup 23
extends. The ball 22 is shown to be integrally formed as part of a tip menber
having a
series of fins or rings 21, as well as a central passage 18. As shown in FIG.
6, a ball
27 is partially inserted into a socket cup 28 that is connected to a tubular
portion 29.
2o This ball and socket joint is generally designated by the numeral "25" ,
and the tip
portion illustrated also includes a series of fins 26. As illustrated in FIG.
6, insertion
of ball 27 into the cup-shaped socket 28 causes deformation of the cup as well
as the
generation of stresses in the respective components. FIG. 7 illustrates ball
and socket
joint insertion forces that are generated upon insertion of the ball into the
socket.
25 As noted earlier, ear wax can partially or completely occlude the tip
member of
the device at a location proximal to the tympanic membrane, thereby leading to
a sharp
reduction in the user's perceived sound quality. FIGS. 8-10 illustrate a
preferred
feature of the invention that is adapted to avoid the detrimental effects of
occlusion of
the tip member. The ear tip members 60, 70, and 80 (FIGS. 8-10, respectively)
each
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16
include multiple, thin, compliant fins, which form a seal in the ear canal.
The tip
embodiments illustrated in FIGS. 8-10 differ from those previously described
in that
they are not connected to the remainder of the hearing instrument by a joint;
instead,
they conform to the ear canal by deformation along their length as will be
described
s later.
In FIG. 8, ear tip member 60 lacks a cerumen guard to prevent cerumen
ingress, thereby exposing an end opening 61 to encroachment by wax which can
result
in the sound port or sound tube 62 becoming at least partially occluded. This
is the
passage through which acoustic signals are communicated. Such occlusion can
lead to
the distortion and attenuation of the sound transmitted from the receiver 63
to the
tympanic membrane through sound port 62. Nevertheless, tip member 60 can be
adapted so that it can be intentionally removed from the remainder of the
hearing
instrument. Accordingly, it can be replaced periodically to eliminate the
cerumen build
up.
is As an alternative solution to this problem, cerumen "guards" have been
devised
as will be disclosed. As seen in FIGS. 9 and 10, it is preferred that the
guards
comprise a thin, flexible membrane positioned at the distal end portion of the
tip
member in order to keep cerumen from entering the sound port, yet while
remaining
substantially acoustically transparent. Whether or not acoustically fully
transparent,
2o the guards should be capable of transmitting acoustic signals between the
ear canal and
the tip's passage.
FIG. 9 shows an ear tip member 70 that is substantially similar to tip member
60, but with a wax guard membrane 73. Membrane 73 may be molded at the same
time as ear tip 70 so as not to add any significant cost to the item.
Alternatively, it can
zs be assembled onto an end surface of the tip. The membrane may be of any
thickness,
but the membrane is preferably in the range from about 0.125mm to .0375mm (0.5
to
about 1.5 mils) thick and the membrane most preferably is about 0.25mm (1.0
mils)
thick. Membrane 73 should preferably be thin enough to let most of the
acoustical
energy pass through. It is preferably made of a low-modulus, tear resistant
and
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17
durable material, such a C-FLEX' available from Consolidated Polymer
Technologies,
Inc. Other materials can be used; preferably, Liquid Injection Moldable (LIM)
materials such as silicone. A Shore A durometer less than about 5 is also
preferred. If
cerumen collects on the membrane 73, the user may easily clean the surface,
with a
simple wiping action, for example. Membrane 73 will substantially prevent
certunen
from entering and blocking sound channel 71. Accordingly, passage or sound
port 71
remains substantially free from obstruction to permit the communication of
acoustic
signals from the receiver 72 from which it extends.
FIG. 10 illustrates an alternative membrane configuration for the wax guard. A
compliant surround portion 84 attaches the central portion of the wax guard 83
to the
rest of the ear tip member 80. Compliant surround 84 portion allows membrane
83 to
vibrate more freely as compared to the configuration shown in FIG. 9, thereby
permitting more acoustical energy to pass from the receiver to the tympanic
membrane
of the ear.
~5 In the configurations of FIGS. 9 and 10, it has been discovered that the
wax
guard membranes 73 and 83 beneficially act as an acoustical filter. By
adjusting the
thickness or material properties of the membranes 73, 83, they may be tuned to
alter or
improve the subjective sound quality of the hearing aid. These properties can
be
manipulated to dampen the mechanical and acoustical resonances of the
receiver, sound
2o channel, and ear canal, thus providing a smoother frequency response. The
membranes are most preferably adapted to minimize or eliminate attenuation of
the
acoustic signals.
Although the exact configuration of the shell (such as item 1 in FIG. 1) is
not
critical to the invention, it has been discovered that preferred embodiments
of the shell
25 can significantly reduce the cost of manufacturing a hearing instrument
according to
this invention.
Of all the components in a hearing aid, the microphone and receiver
(loudspeaker) are perhaps the most costly. Of these two, the receiver is often
the more
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18
costly item. Knowles Electronics, Inc., of Itasca, Illinois (USA), and
Microtronics, of -
Amsterdam, The Netherlands, produce a variety of microphones and receivers
that are
currently used in hearing aids. The typical cost of these components is as
much as
about $25(US) or more for the pair (microphone and receiver). To lower the
cost of
s manufacturing hearing aids significantly, the cost of the microphone and
receiver
components should be reduced. It is one of the goals of this invention to
lower this
cost by integrating the receiver into the hearing insmunent housing.
Conventional receivers can be described as self-contained receivers that are
traditionally mounted in a metal receiver housing. In general, conventional
receiver
t o housings have small solder pads to which small wires are soldered to make
electrical
connection to the receiver. The soldered connections are often fragile and can
easily
break. In manufacriiring a conventional hearing aid, great care must be
observed so as
not to damage the receiver or soldered connections.
According to a preferred aspect of this invention, the internal components of
the
~5 receiver are integrated with the housing, or shell, of the hearing
instrument. The
conventional metal housing of the receiver is not used; rather, the shell of
the hearing
instrument also serves as the housing for the receiver components in order to
provide a
lower cost hearing aid system and to provide more room for the receiver
because the
conventional metal housing of the receiver is no longer needed. Such
construction also
2o permits the use of larger, more robust wires with which electrical
connections to the
receiver can be made. With more room available for the receiver components,
larger
and lower cost components can be used.
In one embodiment, referring back to FIG. 1, the motor assembly (not shown)
of the receiver is mounted in the lower shell portion 1B of the shell 1. The
diaphragm
25 (not shown) for the receiver is mounted in the upper shell portion of lA of
shell 1. A
drive pin (not shown) extends from the motor assembly. A drop of adhesive
(e.g.,
epoxy) is applied to the drive pin, and the two shell portions lA and 1B are
brought
together. The shell portions are sealed either by solvent sealing, adhesives,
ultrasonic
welding, or other known methods. Wire leads pass through holes (or slots) in
the
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19
lower shell portion 1B of shell 1, and are used to make electrical connection
to the
receiver. These wires may be bent into a position so that a flex-circuit
assembly,
containing the hearing aid electronic circuitry, can easily be secured to the
wires. The
motor assembly is preferably secured in place using an adhesive, such as
epoxy, or a
snap connection. The diaphragm is preferably secured to the upper shell
portion lA of
shell 1 with an adhesive, by solvent sealing or by other known methods.
Referring now to FIGS. 16 and 17, an embodiment of a hearing instrument 300
is illustrated in which a balanced armature-type receiver is utilized. Hearing
instrument 300 includes an upper shell portion 302 and a lower shell portion
304. The
Zo upper shell portion 302 is configured in such a way as to form a sound
chamber 306.
An outlet sound port 308 permits the transmission of output sound "A"
outwardly
from sound chamber 306. A diaphragm 310 is mounted to upper shell portion 302
adjacent to (and at least partially enclosing) sound chamber 306. Diaphragm
310 is
mounted to upper shell portion 302 by means of adhesive or other equivalent
bonding
or mechanical means. Diaphragm 310 includes a drive pinhole 312 which is
provided
to accommodate the drive pin of a motor assembly, preferably a moving armature
transducer, as will be described later.
Lower shell portion 304 is provided with contours that define a comparitnent
314 which is positioned and sized to accommodate a motor assembly 316.
Electrical
2o connections 318 are provided for connection between motor assembly 316 and
other
hearing instrument components (not shown). Drive pin 320 extends upwardly from
motor assembly 316. It is positioned so that it will extend through drive
pinhole 312 in
diaphragm 310 when upper and lower shell portions 302 and 304 are brought
together
during assembly. FIG. 17 provides a cross-sectional end view substantially
along the
axis of hearing instrument 300 to further illustrate features of this
embodiment.
Proper positioning of the motor assembly and the diaphragm is critical in this
embodiment to assure that the drive pin of the motor assembly is aligned with
a small
hole in the diaphragm. This is especially true when the motor assembly is part
of a
balanced armature-type receiver. For example, a moving armature transducer
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generally includes a non-movable coil on a magnetic structure. A moving
armature
completes the magnetic path. As current in the coil varies, the force on the
armature
varies and the armature moves. The armature may be attached to a separate
diaphragm, or it may be the diaphragm itself. Moving armature transducers may
be of
s the balanced-armature or unbalanced armature types. In general, the balanced-
armature type has lower distortion than unbalanced-armature types. However,
the
balanced-armature structure may require two matched magnets as compared to the
unbalanced-armature construction which uses only one magnet.
When the two half shell portions lA and 1B are brought together, visual
to alignment cannot be used because the drive pin of the motor assembly and
diaphragm
are hidden by the shell portions. The diaphragm and upper shell portion lA
form a
sound chamber in which an output sound port is located. Electrical current
passing
through the voice coil of the motor assembly causes the drive pin to vibrate,
which in
turn vibrates the diaphragm. The sound pressure created in the sound chamber
escapes
15 through the output sound port. A very small hole (not shown) in either the
diaphragm
or the lower shell portion 1B provides means for atmospheric pressure
equalization.
In another embodiment, also comprising a balanced armature-type receiver, the
diaphragm is also mounted in the lower shell portion 1B together with the
motor
assembly. After the motor assembly is mounted in the lower shell portion 1B,
the
2o diaphragm is mounted in the lower shell portion 1B with the drive pin of
the motor
assembly extending through a small hole in the diaphragm. A small drop of
adhesive,
such as epoxy, is then applied to the drive pin to secure it to the diaphragm.
Unlike in
the previous embodiment, alignment of the diaphragm and the motor assembly's
drive
pin can be made by visual means. Also, machine (automated) assembly is made
easy
because alignment of all of the receiver components can be referenced to a
single half
shell portion (in this case, shell portion 1B). Accordingly, alignment of the
upper and
lower shell portions lA and 1B is not as critical as it is with the previous
embodiment.
FIG. 18 provides a cross-sectional side view of an embodiment of a hearing
instrument 400 that includes a balanced armature-type receiver wherein the
diaphragm
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21
is also mounted in the lower shell. Hearing insmunent 400 includes an upper
shell
portion 402 and a lower shell portion 404. A sound chamber 406 is provided in
the
upper shell portion 402 and an outlet sound port 408 is provided for the
communication
of output sound "A" . Lower shell portion 404 is provided with a surface to
which
diaphragm 410 is mounted. Lower shell portion 404 accommodates a motor
assembly
416. Specifically, a compartment 414 accommodates a receiver motor 422 and an
adjacent compartment accommodates various electronic components 424, including
a
microphone 426. In this Figure 18, a drive pin 420 connected to receiver motor
422 is
shown to be extending through a hole in diaphragm 410.
1o The previously described embodiments of the invention relating to the
receiver
housing include a typical balanced armature-type receiver such as those
manufactured
by Knowles Electronics and Microtronics in which a drive pin is used to
transfer the
vibrations of the armature to the diaphragm. In yet another embodiment, the
balanced
armature-type receiver is replaced by an electrodyna~mic loudspeaker in which
the voice
i5 coil is mounted directly to the diaphragm. Such an electro-dynamic
loudspeaker (or
moving coil transducer) generally includes a coil attached directly to a
diaphragm. The
coil is positioned within a magnetic field. Current passing through the coil
creates a
force that moves the coil and hence the diaphragm. Such electrodynamic
loudspeakers
are available from many sources and are also known as moving coil
loudspeakers. A
2o permanent magnet assembly, which provides the needed magnetic field, is
preferably
mounted in the lower shell portion IB. Thin, flexible wires are provided on
the voice
coil and are connected to wire leads that provide the means to connect the
loudspeaker
to the hearing aid electronic circuitry.
An embodiment of a hearing instrument 500 including an elecuodynamic
25 loudspeaker is illustrated in FIG. 19. As with the previous embodiments, an
upper
shell portion 502 is configured to define a sound chamber 506 as well as an
output
sound port 508 for outward communication of output sound "A." A diaphragm 510
is
mounted to the lower shell portion 504 and a voice coil 512 is mounted to a
surface of
diaphragm 510. Positioned within a compartment 514 in lower shell portion 504
is a
3o permanent magnet assembly 516. The voice coil 512 is connected to other
hearing
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22
instrument components (not shown) by means of electrical connections 518.
As mentioned previously, a moving armature type loudspeaker can also be
used. The advantage of the moving armature type loudspeaker over the
electrodynamic
loudspeaker is that the voice coil does not vibrate with the diaphragm. This
allows
more turns to be used in the voice coil to permit operation at lower currents.
For
hearing aid applications, low current, and hence low power, is highly
desirable.
FIG. 20 illustrates a cross-sectional side view of another embodiment of a
hearing instrument 600 which includes an unbalanced moving armature type
loudspeaker. Upper shell portion 602 defines a sound chamber 606 adjacent to
an
output sound port 608 for output sound " A. " Lower shell portion 604 provides
a
mounting surface for diaphragm 610 which is a magnetic diaphragm adapted for
unbalanced moving armature type loudspeakers. Lower shell portion 604 provides
a
compartment 614 that is sized and shaped to accommodate a magnet assembly 616
within which is positioned a voice coil assembly 612. Voice coil assembly 612
is
t 5 connected electrically to other hearing instrument components (not shown)
via
electrical connections 618.
An electret loudspeaker (electrostatic loudspeaker) can also be used. The
electret loudspeaker is simple in construction and does not contain a voice
coil. The
voice coils needed in the other loudspeakers use fine gauge wires and may be
fragile.
2o The electret loudspeaker uses a construction similar to low cost electret
microphones.
in general, electrostatic transducers include two parallel plates, one of
which is a thin
flexible membrane. A charge is imposed on the plates either by applying a do
voltage,
or by inserting charge into a dielectric (electret transducer). The
electrostatic forces
between the two parallel plates cause the plates to move towards each other.
By
25 superimposing an ac voltage, the electrostatic forces will vary and the
diaphragm will
move.
Referring now to FIG. 21, yet another hearing instrument 700 is illustrated.
This embodiment is shown with an electret loudspeaker. Upper shell portion 702
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23
defines a sound chamber 706 that communicates output sound "A" through an
outlet
sound port 708. An electret diaphragm 710 is mounted to lower shell portion
704
adjacent to and above a back electrode 712 which is accommodated within the
back
sound chamber 714 that is formed in lower shell portion 704. Electrical
connections
718 connect electret diaphragm 710 and back electrode 712 to other hearing
instrument
components (not shown).
The embodiments shown in FIGS. 16-21 illustrate that many different
loudspeaker types can be utilized when the hearing instrument receiver is
integrated
into the hearing instrument housing.
t o According to another preferred aspect of the invention, it is desirable to
provide
a "one size fits all" peritympanic hearing instrument. It has been discovered
that the
inclusion of a tip that can sustain large elastic deformations is quite
beneficial. A
major advantage of this type of tip is that it allows deep penetration into
the ear canal
by the hearing instrument. Without such penetration, the development of an
improved
is prosthetic device that occupies the peritympanic region would be difficult
at best.
Several important advantages are conferred by the utilization of a hearing aid
that allows large elastic deformations. The flexible tip enables the
navigation of the
typical, nominally S-shaped centerline path of an ear canal. Post insertion,
the
stationary location of the flexible tip is between the second bend and the ear
drum. In
20 other words, the distal end of the tip of the hearing instrument has
traversed both bends
and has now entered the peritympanic region. By placing the tip so deeply into
the ear,
it is now possible to more efficiently couple the sound emitted from the
receiver to the
ear drum. Therefore, the required output levels of the receiver are reduced,
and lower
gain amplification may be used. The hearing instrument's battery capacity
25 requirements are also reduced, resulting in a smaller battery and a smaller
prosthesis.
The flexible tip also allows the generation of a seal in the bony region of
the ear
canal. It is believed that an appropriate seal in this region will
substantially mitigate
the occlusion effect - whereby low frequency signals and noise are overly
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24
pronounced. It is also noted that, if desired, the flexible tip may be
designed as a
replaceable part. Hence, if the tip were to become overly contaminated with
wax,
rather that attempting to clean it, one could simply remove the old tip and
attach a new
one. A wax guard, such as those described with reference to FIGS. 9 and 10,
would
s obviate such replacement.
The preferred hearing instrument 100 embodying this aspect of the invention is
shown in FIGS. 11-12. Referring to those figures, the tip assembly 102
consists of a
soft, low durometer covering (or hollow body) 104; an integral spring 106; and
some
means for retaining the tip assembly 102 in the body of the hearing
instrument. In this
1o instance, a retaining disk 108 that resembles a washer is attached to the
spring 106 by a
soldering, brazing, welding, or some other suitable joining process.
Alternatively, a
spring having an abrupt increase in diameter could be used for retention, thus
eliminating the need for the retaining disk 108. This spring subassembly 106,
108 is
then preferably inserted into a mold cavity, and the soft tip 104 is then
injection
t5 molded around the spring insert. If desired, spring 106 could be used to
form the
threads shown in FIG. 2.
As shown in FIGS. 11 and 12, hollow body portion 104 of tip assembly 102 is
substantially tubular in shape and is elongated for permitting a continuum of
deformations along its length so that its axis can conform to the axis of the
extcrnal
2o auditory canal in the region adjacent to the tympanic membrane. The outer
diameter of
body 104 is preferably significantly smaller then its length to permit such
deflection.
The hollow body portion 104 includes a passage 110 that extends all the way
through
portion 104 as a channel for the communication of acoustic signals between the
receiver and the tympanic membrane. Alternatively, passage 110 can terminate
at a
25 wax guard membrane as described previously with reference to FIGS. 9 and
10. The
hollow body portion 104 may be provided in a soft outer covering to provide
comfort
to the wearer.
A series of radially outwardly extending rings or fins 112a-112d are
positioned
about the circumference of the body 104 to generate an acceptable acoustic
seal. At
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least about four rings may be provided on the hollow body 104 although it is
contemplated that fewer can be used. Rings 112a-112d are preferably provided
with
reducing outer diameters as they approach the distal end of hollow body
portion 104.
Such a construction provides various ring diameters so that at least one or
two of the
5 rings are appropriately sized to form a seal in the user's ear canal.
Although many
sizes are contemplated, one exemplary embodiment of tip assembly 102 has ring
diameters of 7, 8, 9 and 10 mm, for example. Also, although the rings are
illustrated
as flat plates, the rings can also be contoured. For example, they can be
angled away
from the tympaaic membrane to help guide the tip into the ear canal. Vent
holes (not
to shown) can be provided in rings 112a-112d to vent pressure from the
tympanic
membrane to the atmosphere, although the compliance of the rings can make them
self
venting. Such a structure provides a series of seals against the inner canal
surface and
ensures that at least one will be appropriately sized to seal in a particular
ear canal.
The distal-most ring 112d has the smallest diameter and it is provided with
four
15 centering protrusions 114a-114d extending radially outwardly from the
perimeter
portion of ring 112d. Although four such protrusions are shown in the
exemplary
embodiment, fewer or more can be used as well. In any event, whatever number
is
selected, the protrusions are preferably spaced evenly about the ring's
circumference.
It has been discovered that protrusions such as protrusions 114a-114d confer
2o significant benefits. Specifically, they provide a means for centering the
tip within the
ear canal as it navigates toward the tympanic membrane. The protrusions 114x-
114d
glide along the inner surface of the canal and bend away from the direction of
insertion, thereby centering hollow body 104 in the canal for optimal
positioning and
comfort.
25 Because the rings are thin and constructed of a low modulus, low durometer
material, the tip assembly provides a high level of comfort for the user even
when used
in the bony region of the ear. The rings may be suitably spaced apart from one
another
along the tip's length.
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26
It has been discovered that tip assembly 102 is more comfortable than
traditional custom ear molds. It is contemplated that a tip assembly according
to this
aspect of the invention can be used in conjunction with traditional hearing
aids whether
they are of the In-the-Ear (ITE), In-the-Canal (ITC), Completely-in-the-Canal
(CIC),
or Behind-the-Ear (BTE) type.
The integral spring 106 (FIG. 12) acts as a support that ensures that the
tip's
sound channel does not collapse when the tip assembly 102 is bent upon
insertion by
kinking or other deformation. Spring 106 is an example of one possible means
for
rcsisting such collapse. Other suitable supports can be substituted. Spring
106 is
to preferably a stainless steel or beryllium-copper compression spring that is
helically
wound. It can be replaced, however, with another form of spring such as a
straight
length of spring-tempered rod or a flat cantilever arm that extends along a
length of the
hollow body adjacent to the wall of the passage. Alternatively, spring 106 can
be
replaced by a metallic or plastic or elastic tube or tubular structure that is
at least
slightly more rigid than the remainder of the hollow body portion to resist
the collapse
of the passage upon bending. However, continuous tubing may tend to kink upon
bending and such kinking could change or reduce the cross-section of the sound
passage. The spring can also be replaced by a support in the form of a series
of
unconnected plastic, metallic or elastomeric rings that are embedded in the
hollow
2o body or otherwise positioned adjacent to the passage along the body's
length to prevent
excessive changes in the cross-secrional shape of the passage. Whatever form
of
support is selected, it is preferably adapted to permit the lengthwise angular
deformation of the tip assembly while preventing or resisting undue kinking,
deformation or collapse of the sound passage. Also, the support is preferably
fully or
partially embedded in the hollow body of the tip. If fully embedded, it is not
exposed
to the passage's interior. Alternatively, the support's inner surface can be
flush with
the passage's inner surface wall or can extend within the passage.
FIG. 11 depicts the flexible tip assembly incorporated into the hearing
instrument 100. Instrument 100 includes two mating shell portions 116A and
116B and
3o a proximal shell portion or end plate 118 at the opposite end from tip
assembly 102.
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27
The distal end portions of shell portions 116A and 116B include semi-circular
recesses,
together defining a substantially circular opening when shell portions 116A
and llbB
are assembled, into which the proximal end of tip assembly 102 extends.
The diameter of the shell opening is slightly smaller than the diameters of
retaining disk 108 and a flange 105 this is preferably located at the proximal
end of
hollow body portion I04. Accordingly, when shell portions 116A and 116B are
mated
together during assembly, flange 105 and retaining disk 108 are captured
within the
shell's interior to prevent inadvertent separation of tip assembly 102 from
the shell. In
other words, the tip assembly is retained due to the capture of the tip
assembly's flange
1o by the shell. Because there is a retaining disk (or equivalent) and a
flange, the tip
assembly will be relatively difficult to remove from the shell. This is a
safety feature
that prevents the tip assembly from accidentally separating from the main.
hearing aid
body.
Enclosed in assembled shell 116A, 116B are additional components of the
t 5 hearing instrument, including a microphone 101, a circuit board 103, and a
receiver
105.
Still referring to FIG. 11, another aspect of this hearing aid design is that
the
angle between the axis of the flexible tip 102 and the axis of the end portion
of the shell
has been selected to optimize the retention of the hearing aid in the ear
canal.
20 Many conventional hearing aids tend to work their way out of the ear canal
due
to common activities of the user such as talking and chewing that can result
in moving
of the user's jaw. Flexible tip 102 is positioned past the second bend and
tends to lock
the hearing aid in position.
In order to help overcome this problem, the angle x between the tip and body
is
25 preferably between about 20° and about 50° and is most
preferably between about 36°
and about 40 ° . An angle x of about 38 ° is especially
beneficial.
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28
Referring now to FIGS. 13-15, another embodiment of a tip assembly is
illustrated and is generally designated by the numeral "202." It includes an
elongated
hollow body portion 204 that is substantially tubular along its length to
define an
elongated acoustic signal passage 210, which extends all the way through tip
assembly
202 from its proximal end to its distal end or terminates at a wax guard
membrane as
described previously with reference to FIGS. 9 and 10. Tip assembly 202
includes a
plurality of fins or rings 212a-212d, each of which extends radially outwardly
from
hollow body portion 204. Tip assembly 202 includes four such rings 212a-212d
that
are spaced at an equal distance along the length of hollow body portion 204.
Around
the outer circumference of each ring 212 are positioned four radially
outwardly
extending protrusions 214 which are spaced at equal distances about the
perimeter of
each ring 212x-212d.
As is most clearly illustrated in FIG. 15, the outer diameters of rings 212x-
212d
gradually increase from the smallest ring 212d which is positioned adjacent to
the distal
t s end of tip assembly 202. In this embodiment, each of the protrusions 214
have
substantially the same length and extend to increasingly larger
circumferential positions
as the diameters of the respective rings on which they are mounted enlarge.
As with the previous embodiment of the tip assembly 102, the rings 212x-212d
are provided on tip assembly 202 in order to ensure a seal between the tip
assembly
2o and the inner surface of the user's external auditory canal. Also,
protrusions 214 act to
center the tip assembly 202 within the ear canal as it is inserted toward the
tympanic
membrane so that the passage 212 and the hollow body portion 204 remain
centered
within the canal.
Although the invention has been described with reference to particular
25 embodiments selected for illustration, it will be appreciated that many
modifications
can be made without departing from the scope of the invention.
Although it may be preferred to provide a tip portion having a predefined
single
or multiple degree-of freedom joint for connection to the body of the hearing
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29
instrument, it should be appreciated that such a joint can be eliminated in
its entirety
and that a flexible tip member having a hollow body portion capable of
significant
deformation along its length can be used in order to conform the hearing
instrument to
the individual's external auditory canal. If a joint is used, it is preferably
adapted to be
positioned in the vicinity of the canal's second bend, but can be positioned
elsewhere
within the ear canal, as desired. A ball and socket style faint can be used
but other
known joints can be substituted depending on the application. If indeed a ball
and
socket joint is used, then the ball is optionally positioned on the hearing
instrument's
shell or on the instrument's tip. Similarly, the socket of the joint can be
positioned on
1o either one of the instrument's tip or shell components.
A wide variety of materiais can be selected for use in forming the flexible
tip
member and the relatively rigid shell. Preferred materials have been described
but they
can be replaced with equivalent materials that can be selected at the
discretion of the
manufacturer of the hearing instrument. The tip of the hearing instrument is
preferably
t 5 provided with a guard or membrane in order to resist the ingress of
cerumen into the
acoustic signal passage; nevertheless, such a guard or membrane can be
eliminated and
the tip can simply be cleaned or replaced with a new tip periodically at the
user's
discretion.
The fins or rings positioned on the hollow body member can be provided in any
2o number and size although it is preferred that they are designed in order to
maintain an
adequate seal between the tip and the inner surface of the user's canal.
Similarly, the
protrusions or flanges that extend outwardly from the hollow body portion or
from the
fins can be provided in any number in each plane or along the length of the
hollow
body portion, or they can be eliminated entirely.
25 Several exemplary and specific types of receivers and receiver components
have
been described for the purpose of illustration but it will be appreciated that
the
disclosed components can be substituted for equivalent components. Also, the
various
manufacturing processes that are described herein for the assembly of the
hearing
instrument as well as the method of producing the various components (i.e., by
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WO 99/39548 PCT/US99/00150
injection molding, for example) can be substituted with equivalent assembly
and
manufacturing processes.
It will be appreciated that the spring 106 described as part of the tip
assembly
102 is one example of a means for resisting or preventing the collapse of the
passage to
5 the hollow body portion. It will be appreciated that many alternative means
can be
substituted including tubular structures, spaced ring segments, cantilever
lengths of
spring-tempered materials, a structural support extending across the passage,
or other
structures that are capable of resisting an excessive change in the cross-
sectional shape
of the passage along its length that would otherwise occur upon bending of the
hollow
1o body portion as it is inserted into the user's ear canal.
Additional modifications are contemplated and the substitution of components
for equivalent components and features is intended to be within the scope of
the
invention as it is defined in the appended claims.
